Register Type Aliases

#include <iostream>
#include <cstdint>
using namespace std;

using Reg8 = uint8_t;
using Reg16 = uint16_t;
using Reg32 = uint32_t;

int main() {

    uint64_t raw8, raw16, raw32;
    cin >> raw8 >> raw16 >> raw32;

    Reg8 r8 = static_cast<Reg8>(raw8);
    Reg16 r16 = static_cast<Reg16>(raw16);
    Reg32 r32 = static_cast<Reg32>(raw32);

    cout << "R8="<< static_cast<uint32_t>(r8) << " R16=" << static_cast<uint32_t>(r16) << " R32=" << r32;

    return 0;
}

Solving Approach